microMETER (patent applied for) Introduction
CAUTION: CT INSTALLATION IS TO BE DONE BY LEGALLY LICENSED
ELECTRICIANS ON 120/240 VOLT SERVICES ONLY (using original
thin-wire CT's). Thick-wire CT's, marked "600v", are UL-approved
for 600v usage. SEE README2 FOR 3 PHASE AND 480 VOLT USAGE.
This is a Class II device and may be installed and serviced by anyone qualified for such.
This device complies with part 15 of the FCC Rules. Operation is
subject to the following two conditions: (1) This device may not cause
harmful interference, and (2) this device must accept any interference
received, including interference that may cause undesired operation.
DISCLAIMERS:
This equipment must be used within legal constraints in the installed location.
This equipment has not been type-approved for commercial use.
There is no implied or otherwise warranty of fitness for a particular purpose.
This equipment must be installed according to instructions provided to perform to
its specification.
Liability is strictly limited to the purchase price and specifically excludes consequential
damages.
This is an educational project with no current commercial, regulatory, or safety certification.
Contents: Page
Description, Specification .... 1
Pre-install Planning .......... 2
Hardware Install .............. 3
Hardware Install cont ......... 4
Hookup Detail ................. 5
Main Board Detail ............. 6
Special Considerations ........ 6.1
README is maintained for accuracy only and in accord
with UL Listing 8F84 (File# E166737).
mMII, introduced in Jan 2004, is the same device using a more
advanced microprocessor from the same manufacturer as the first.
1 - Description, Specification
The microMETER is a low-cost digital electric power submetering
system. It reports demand and total accumulated power for 16
circuits through an RS232 communication link to a computer.
Standard Equipment Package
Standard CT's (specify sizes 20,40,60,100 amp)
Package: (600 volt-listed avail)
(combination microMETER "J-box" unit containing:
may vary main board with microprocessor
to fit special terminal board for CT leads
needs) ribbon cable
RS232 data cable
Software
Instruction sheet
microMETER Specifications
Power requirements: 29 vac 70 ma (Type 2 - a Class 2 device)
Inputs 23 mvrms full scale x 16 channels
(20 amperes with 20 ampere CT)
Output RS232 300 baud ASCII 8 bit none, 1 stop
CT#, current demand, low bucket, high
bucket - converted to amperes and kwh
Accuracy RMS amperes - +/- 2% (.4% 8-bit repeatability)
RMS apparent power - +/- 2% (.4% 8-bit repeatability)
Watts/avg volts - +/- 2% (.4% 8-bit repeatability)
True Power - +/- 2%* (.4% 8-bit repeatability)
Tested under ANSI C12.1 conditions
as a Class 20 revenue meter with
NIST traceability.
Software Selected programs from:
Billing Suite
Analytical Suite
Utility Suite
Additional Requirement (PT)*
*PT - Third party, separate UL listing
* Verify power transformer for proper input and
output voltages. Any approved Class II device
providing 29 volts with no load other than one
microMETER per 20va may be used to obtain accurate
true power readings.
* The potential transformer (PT) is not part of the "standard package"
listing above as 8F84. A suitable, approved device is re-sold
with the "standard package". It is referred to in various ways as the
"Class 2 - 24-volt control transformer" below. The open circuit voltage
should be about 29 volts.
2 - Hardware Pre-installation Planning
YOU MUST READ THIS SECTION AND WORK OUT AHEAD OF TIME ON A
SHEET OF PAPER THE SEQUENCE OF THE CIRCUITS, WHICH PHASE OF
THE LINE (A or B) EACH IS ON, CT SIZES AND HOW YOU ARE TO
WIRE THE POLARITY OF THE CT's GOING INTO THE microMETER.
Elec Panel Worksheet
9/7/2008 - THIS IS USUALLY DONE IN ADVANCE WITH INTERACTIVE SOFTWARE
AS PART OF THE PACKAGE COST. SUCH PRE-CONFIGURED SYSTEMS WILL FIT
YOUR PANEL EXACTLY. SEE:
Electrical Panel:
Standard Schedule
3-Phase Schedule
1. You will connect a "Class 2" 24v transformer to a circuit
connected to the "A" phase or "B" phase. Note that all other
hook-ups are going to be related to this decision. Example:
you elect the "A" phase. Do not energize until installation
step #4 is complete.
2. Inside the microMETER the terminal strip is numbered
1....16 and each terminal has a positive and a negative
side. See picture.
Since the device reads out its information in the
sequence 1 thru 16, it is essential to wire your circuits in
the same sequence; in other words, in the order in which you
want the circuits to be read out so that the printout of data
won't be all jumbled up. SEE README2 FOR THREE PHASE USE.
3. The leads coming out of each CT are not the same length.
The longer lead is positive, the shorter lead is negative.
All circuits on the same side as the transformer ( "A" phase
selected for the transformer as above) should be wired in to
the microMETER terminal so that the long lead is wired to the
positive side of the terminal and the short to the negative.
DO NOT CUT OR TRIM CT LEADS. THIS WILL VOID WARRANTY.
All circuits on the other side of the service drop, the
"B" phases, must be wired into the microMETER with opposite
polarity, ie, run the long lead into the negative side of the
terminal and the short lead into the positive side. SEE
README2 FOR THREE PHASE USE.
4. In all cases, mount the CT on a fully-insulated load
carrying wire with the terminal leads away from the source.
5. Any single circuit operating on 240 volts can either be
wired with 2 separate CT's or you can run both wires through
one CT of a size suitable for both currents). The second wire
must pass through the CT in the OPPOSITE direction from the
other so that the two currents are added together in the
measurement. If they were both run in the same direction
through the CT, they would cancel each other out and there
would be no measurement. Phase the leads based on the first
wire. A balanced load can be measured with one CT on one side
only and voltage doubled in the software (i.e. water heater).
6. Now, using your sheet of paper as a guide, install in the
above sequence and polarity.
7. Jumper (short out) any unused CT connections on the Terminal Board.
3 - microMETER Hardware Installation
Note (05/21/2003): This applies to mMI and mMII but Cat 5
wiring is used with mMII. The red, green, yellow, and
black color references only apply to Cat 1 cabling used
with mMI. See README2 for Cat5 color codes.
Note (01/19/2006): This applies to mMI and mMII. Cat 1
is no longer readily available. Cat 5 will be used for
all processors and cabling. Color code equivalents are:
Cat 1 Cat 5
green white w blue
red blue
black white w orange
yellow orange
10/21/2008 - Special note about extending RS2325 cable: Only the blue/white pair
needs to be extended. The other pairs are locally looped back or open and
SHOULD NOT BE EXTENDED.
1. Mount the microMETER near the circuits to be monitored.
The CT leads are about 60" long .... if these lengths are
inadequate, longer-leaded CT's are available. DO NOT CUT
OR TRIM THESE LEADS TO EQUAL LENGTH.
************************************************************
A LICENSED ELECTRICIAN SHALL PERFORM STEPS 2 THRU 5.
DO NOT INSTALL IN SERVICE AREAS HAVING MORE THAN 240 VOLTS.
480 VOLT CIRCUITS REQUIRE AVAILABLE SPECIALLY MADE CT'S.
************************************************************
2. Disconnect power to the power line to be monitored.
3. Place CT on the power line. Use 20 amp CTs for circuits up
to 20 amps. These have blue leads. Use larger amp CTs for
larger circuits up to 200 amps. These have leads of another color
(see README2). The CT can be placed anywhere along the fully insulated
wire so that it fits best.
Secure the CT with Nylon ties as shown.
Dress and route CT leads out of the access area through the
nearest knockout access hole using an approved fitting.
4. Open the microMETER box. Do NOT detach the terminal board from
the ribbon cable. Pass CT leads through the box port and
attach the CORRECT (see above) wire to the + terminal and the
other one to the corresponding - terminal. Dress the leads to
run along the terminal board and ribbon so the box can be
closed.
Check to make sure the yellow, black, red and green wires
are in place (see illustration below).
Carefully close the microMETER box, but don't put all screws
in until everything checks out.
If installed outdoors, make connections to the microMETER box
with suitable fittings to keep out moisture. Shade it from sun.
4 - microMETER Hardware Installation cont
5. Install an approved "Class 2" 24-volt transformer (29
volts unloaded) near the microMETER location using an
approved J-box. This is the PT described on page 1.
6. Connect the de-energized control transformer to the black
and yellow lead pair from the microMETER. See Addendum in README2.
29v transformer microMETER I mMII (w Cat5)
------ terminal A to yellow-------
orange
------ terminal B to black--------
white w orange
7. Attach the RS232 cable to PC or modem and connect to
the red and green microMETER lead pair as shown:
RS232 cable microMETER I mMII (w Cat5)
------------red to red----------
---- test blue
----------green to green--------
--- LED white w blue
8. Apply power to the Class II transformer. Verify that the LED
flashes every 10 seconds (on main board or at RS232 connection).
The black and yellow wires from the RS232 plug can be taped
aside. Don't cut them off, they may be needed for a future
enhancement. A modem must be hardware-set to auto answer.
This cable may be extended (See Special Considerations
below.)
NOTE: RS232 cables support RX, TX and ring detect. All have
the same wire color code:
Green - signal ground (connect to microMETER green wire)
Red - RX data (connect to microMETER red wire)
Yellow - TX data (for future use)
Black - ring detect (for future use)
5 - Hookup Detail
6 - Main Board Detail Showing Internal Connections
See picture.
6.1 - Special Considerations
Use #22 or #24 gauge solid twisted pair telephone wire to
extend connections to no more than 300 feet. When making
long cable runs between buildings, care must be taken to
avoid lightning surge damage.
THE MOST EFFECTIVE ESD PROTECTION IS TO CONNECT THE RS232 LINE
TO THE microMETER AND THE PC ONLY WHEN TAKING MONTHLY READINGS.
DISCONNECT AT BOTH ENDS WHEN NOT TAKING READINGS.
Shielding in metal conduit and surge suppressors of the type
designed for telephone equipment should be used for any line
entering the microMETER, modem or PC that exceeds 20 feet.
This is a necessity for marina slips or RV parks. Cables must
be carefully placed to avoid excessive interference pickup and
grounding due to abrasion. A special terminal board (inside
the microMETER) with additional RF suppression components may
be needed in certain hostile environments. Test the long CT
lines with known loads to note any anomalies. Zero loads
should produce zero signal. Any phantom signal may be due to
grounding or RF pickup. Avoid any separation of the twisted-
pair conductors, particularly at splices.
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See README2 file for software installation and additional information.
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